An electrical battery includes one or more electrochemical cells that convert stored chemical energy into electrical energy. Batteries have become a common power source for many household and industrial applications. There are two types of batteries: primary batteries and secondary batteries. Primary batteries are disposable batteries designed to be used once and discarded. Secondary batteries are rechargeable batteries designed to be recharged and used multiple times. Batteries come in many sizes. They range from miniature cells used to power hearing aids and wristwatches to battery banks that are the size of rooms that provide standby power for telephone exchanges and computer data centers.